With the research progress and characteristics of low flow frequency analysis, a new low-flow frequency distribution-an extension of three-parameter Burr Ⅲ distribution developed by the Australian is introduced. The extension of three-parameter Burr Ⅲ distribution is flexible to approximate extreme value distribution, which is used in Liujiazhuang hydrological station in Qingzhang River. With the Pearson-Ⅲ(P3) model for comparison,a good level in fitting and forecasting is exhibited by the low-flow model with the real measured low flow series and statistical tests. In terms of dealing with the tail of frequency curve and high reliability level design values less than zero, it is better than the P3 model. The extended three parameter Burr Ⅲ distribution is, therefore, a meaningful candidate distribution in the frequency analysis. Maximum likelihood estimation for this distribution is investigated.%概述了枯水频率分析的研究进展,结合枯水频率分析的特点,以南运河系清漳河刘家庄水文站的枯水径流系列为研究对象,采用一种新的模型--邵氏扩展3参数BurrⅢ型分布,并与皮尔逊Ⅲ型(P3)模型进行比较.统计检验结果表明,该模型与皮尔逊Ⅲ型拟合和预测效果都比较好.特别是在处理频率曲线尾部出现水平以及较高保证率下设计值小于零的问题上,要优于P3分布.并采用极大似然法进行参数估计,为枯水频率分析提供了一条新的途径.
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